Pre-deformed Thermoplastic Spring Creep Resistance
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Solution Overview
Problem
Thermoplastic springs used in applications like railroad air hose support straps face issues such as creep, elongation, and breakage, leading to frequent failures and increased maintenance costs, which existing technologies have not adequately addressed.
Innovation Solution
A pre-deformed thermoplastic spring with integral end details and deformed regions is molded to achieve specific spring rate and creep resistance, allowing for elongation and recovery in a single injection-molded part, reducing the risk of breakage and elongation through programmed deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a thermoplastic strap is stretched beyond its yield point to increase length, then the strap length increases, but the strap develops permanent deformation (creep) and loses its elastic recovery capability
Solution Approach 1:
The patent applies preliminary action by pre-deforming the thermoplastic spring during manufacturing to a predetermined length that programs the desired creep resistance and spring tension. This pre-deformation establishes the final dimensions and elastic properties before the product is put into service, preventing future unwanted creep under operating conditions.
Solution Approach 2:
The patent changes the physical parameters of the thermoplastic material through controlled deformation to a predetermined length. This parameter change programs the material's creep resistance and spring tension, transforming it from a simple elastic member prone to creep into a pre-deformed spring with optimized mechanical properties.
2Strength
If metal coil springs are used to provide spring-loaded mechanical assemblies, then sufficient strength and elasticity are achieved, but rust, noise, metal fatigue, and sharp hooked ends occur
Solution Approach 1:
The patent replaces traditional metal coil springs with elastomeric thermoplastic springs that are corrosion-resistant and eliminate noise from metal-on-metal contact. While elastomeric materials have different lifecycle characteristics, this substitution eliminates rust and noise issues inherent to metal springs.
Solution Approach 2:
The patent uses elastomeric thermoplastic materials that combine the benefits of plasticity and elasticity in a single molded part. This composite material approach replaces metal components with an elastomeric material that provides sufficient strength while eliminating rust and noise problems.
3Object-affected harmful factors
If elastomeric straps are used instead of metal springs, then rust and noise are eliminated, but the straps develop creep and become inadequate for their intended purpose over time
Solution Approach 1:
The patent applies preliminary action by pre-deforming the elastomeric thermoplastic spring during manufacturing to program the desired creep resistance. This pre-deformation establishes the final dimensions and elastic properties before service, preventing future unwanted creep under operating conditions.
Solution Approach 2:
The patent changes the physical parameters of the elastomeric material through controlled deformation to a predetermined length, programming the material's creep resistance and spring tension. This transforms the material from a simple elastic member prone to creep into a pre-deformed spring with optimized mechanical properties.
4Ease of manufacture
If air hose support straps are not sufficiently strong, then installation is easier, but frequent breakage and elongation occur leading to increased maintenance costs
Solution Approach 1:
The patent applies preliminary action by pre-deforming the thermoplastic spring during manufacturing to program the desired creep resistance and spring tension. This ensures the product arrives at the installation site with optimized mechanical properties, eliminating the need for field adjustments and ensuring immediate reliability.
Solution Approach 2:
The patent changes the physical parameters of the thermoplastic material through controlled deformation to a predetermined length, programming the material's creep resistance and spring tension. This ensures the support strap has sufficient strength to prevent breakage and elongation during service.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides enhanced creep resistance and spring tension, reducing the likelihood of failures and meeting revised industry standards for air hose support straps, such as AAR S-4006-03, by allowing the thermoplastic spring to maintain its shape under load without further elongation.
Implementation Method 1
deformed regions designed to perform elongation and recovery all in one injection molded member
Implementation Method 2
A thermoplastic strap of proper length and tension when new can become inadequate for its intended purpose when creep exceeds even a small amount
Data Source
AI summary
A thermoplastic spring and a method for manufacturing the thermoplastic spring are provided to reduce the effect of creep during use of the spring. The spring is molded and deformed to final dimensions by pre-inducing creep in the molded body.